1. Field of the Invention
The present invention relates to a frequency modulated continuous wave (FMCW) radar device and an FMCW radar signal processing method for detecting an object serving as a target (hereinafter simply referred to as “target”), and measuring a distance to the target and a speed relative to the target.
2. Description of the Related Art
In recent years, an FMCW radar device (hereinafter also simply referred to as “FMCW radar”) is used, which can deal with a target at a distance of several hundred meters with a less expensive and simpler configuration than a pulse radar and other radars. The FMCW radar radiates (transmits) a transmission signal subjected to specific modulation as an electromagnetic wave, receives the electromagnetic wave reflected by a target as a reception signal, and generates a beat signal based on the transmission signal and the reception signal.
Further, the beat signal is converted into digital data by an AD converter (analog-to-digital converter: ADC), and is then input to a central processing unit (CPU) or the like. The CPU performs signal processing, to thereby detect the target and measure a distance to the target and a speed relative to the target.
As such FMCW radar device, the following FMCW radar device is known. In order to detect a plurality of targets over a wide range and to measure a distance to each of the detected targets and a speed relative to each target, the FMCW radar device includes a plurality of band-pass filters (BPFs) having different pass bandwidths prepared for respective range observation periods corresponding to the ranges where the targets are detectable, and the BPFs are switched for each range observation period (see, for example, Japanese Patent Application Laid-open No. 2013-88273).
However, the related art has the following problem.
Specifically, the related-art FMCW radar device switches the BPFs by using switches for each range observation period in order to detect the plurality of targets over a wide range and to measure the distance to each of the detected targets and the speed relative to each target. Accordingly, the related-art FMCW radar device needs to include the plurality of BPFs and switches, resulting in a problem in that the device is expensive.